Linkage disequilibrium (LD) makes identification of causative SNPs challenging. In a typical region of the human genome, many SNPs (orange box) are in strong LD with the tag SNP (red) identified by a GWAS study. Genome editing can be used to identify the causative lesion from within this LD block. LD is measured as R-squared values between pairs of SNPs, and indicated on the heatmap
